The goal of this clinical trial is to evaluate the diagnostic performance and safety of Flotufolastat F-18 injection PET imaging in prostate cancer subjects with biochemical recurrence following prior treatment. The main question it aims to answer is:

• What is the correct detection rate of Flotufolastat F 18 injection PET visual reading results compared to the truth standard?

Participants will:

• Receive Flotufolastat F-18 injection
• Undergo PET/CT scanning

Inclusion Criteria:

1. Fully understand the study and voluntarily sign the informed consent form. 2. Male, aged ≥18 years. 3. Has previously received one or more of the following treatments:

1. Radical prostatectomy (RP);

2. RP with adjuvant radiotherapy (RT);

3. RP with adjuvant androgen deprivation therapy (ADT);

4. Radical RT or focal gland therapy (e.g., brachytherapy, high-intensity focused ultrasound [HIFU]).

   4. Clinically suspected BCR, serum PSA levels should meet at least one of the followings:

   1. After RP with or without adjuvant or salvage therapy: PSA≥ 0.2 ng/mL, and subsequent confirmation that PSA ≥ 0.2 ng/mL.
   2. After RT as primary treatment: PSA increased at least 2 ng/mL compaire to the nadir.
   3. After focal gland therapy as primary treatment: PSA increased at least 2 ng/mL compaire to the nadir.

   5. If positive lesions are detected on the XTR020 PET imaging or conventional imaging, the subject is willing to receive histopathological confirmation or the sequqnce of conventional imaging confirmation.

   6. Male subjects with reproductive potential must use effective contraception during the study period and 6 months after the study completed; their partners should agree to use contraception during the study period and 6 months after the study completed , too.

   Exclusion Criteria:

   1. Planned to receive an X-ray contrast agent or other radioactive imaging agent within 24 hours before XTR020 PET imaging.
   2. Participation in an interventional clinical trial involving a new drug or treatment within 30 days or 5 biological half-lives of the drug prior to XTR020 PET imaging (whichever is longer).
   3. Known allergy to the active ingredient or any excipient of XTR020.
   4. Claustrophobia or inability to tolerate imaging examinations for any other reason.
   5. Poor compliance or deemed unsuitable for participation in this study by the investigator.
   6. Any condition that, in the opinion of the investigator, may interfere with data collection or prevent the study requirements.